1. Technical Field
The present invention relates to a liquid droplet ejection apparatus and to a pressure-regulating valve for vacuum-feeding a functional liquid to a functional droplet ejection head.
2. Related Art
A known pressure-regulating valve of this type for vacuum-feeding a functional liquid to an inkjet-type functional droplet ejection head is disclosed in Japanese Laid-open Patent Publication No. 2006-82538. This pressure-regulating valve has a primary chamber communicated with a functional liquid tank; a secondary chamber communicating with a functional droplet ejection head and composed of a diaphragm in the form of a film in which one wall surface has a pressure-receiving plate; a communication flow passage for allowing the primary chamber and the secondary chamber to communicate; and a valve body for opening and closing the communication flow passage. A shaft portion inserted through the communication flow passage so as to come in contact with the diaphragm is provided in protruding fashion to the valve body, and the valve body is opened and closed by the action of the diaphragm.
For example, when the pressure of the secondary chamber decreases in conjunction with ejection by the functional droplet ejection head, the diaphragm (pressure-receiving membrane) deforms inward, and the valve body opens via the shaft portion. When the valve body opens, the functional liquid flows in from the primary chamber, the secondary chamber is pressurized, the diaphragm returns to the original shape, and the valve body closes.
However, the diaphragm (pressure-receiving membrane), which acts at atmospheric pressure, is composed of a film in the conventional pressure-regulating valve described above, and may therefore be affected by surrounding air currents. When the diaphragm is affected by an air current, i.e., an external force other than atmospheric pressure, the deformation or action of the diaphragm is disrupted, and the opening and closing of the valve body become unstable.